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Abstract

Recently, diffuse speckle contrast analysis (DSCA) was introduced as a competent modality for deep tissue blood flow measurement, where the speckle contrast is calculated over spatial domain on the CCD image of diffuse reflectance. In this paper, we introduce time-domain DSCA where temporal statistics are used for speckle contrast calculation and results in the same deep tissue flow measurement. This new modality is especially suitable for multi-channel real-time flowmetry, and we demonstrate its performance on human arm during cuff occlusion test. Independent component analysis (ICA) study on multi-channel data shows promising results about underlying physiology.

Figures (5)

Theoretical calculation of 1/K2 as a function of αDb over a broad range. Red box region, which is magnified in the inlet, refers to the region where αDb is in the physiological range. A good linearity is observed between 1/K2 and αDb within the physiologically relevant region. In this simulation, µs’ = 8 cm−1, µa = 0.03 cm−1, β = 0.5, and the exposure time of 0.2 ms was used.

Schematic of (a) tDSCA setup and (b) the phantom experiment. S1, S2 and S3 are 50:50 fiber splitters, PD is photon detector for power monitoring. Small glass beads are filled inside the hollow tube which is embedded in the solid phantom to provide randomized interstitial space for the flow.

(a) Relationship between αDb and flow rate measured by DCS on the flow phantom. (b) Dependence of 1/K2 on BFI, measured on three different tDSCA channels. Note the x-axis is αDb not flow rate, as we converted flow rate into αDb using the linear relationship shown in Fig. 3(a). The simulation result from Eqs. (2)-(3) is also plotted in (b) for comparison.